Because a diamond has a superior semiconductor characteristic in addition to superior mechanical, chemical, and thermal characteristics, the diamond has attracted attention as a material for a semiconductor device. Particularly, because the diamond has a band gap of about 5.5 eV at room temperature, the diamond has been expected as a material for an ultraviolet emitting device or an electron emitting device using negative electron affinity. In addition, because the diamond has high insulation breakdown resistance, the diamond has been expected as a material for a power device. From high crystallinity, the diamond has been expected as a material for an environmentally resistant device used under a severe environment such as a high temperature or radiation in particular.
The power device manufactured by the diamond has been developed recently. For example, a Schottky barrier diode having a Schottky junction, a device having a PIN structure, and a device in which the Schottky junction is combined with a PN junction have been reported.
In order to realize practical use of the power device manufactured by the diamond, a device structure that enables a high dielectric breakdown voltage of the diamond to be sufficiently used has been expected.